Efficiency-optimizing, calibrated sensorless power/energy conversion in a switch-mode power supply

ABSTRACT

An intelligent pulse width modulation (PWM) controller adapts a switch mode power supply (SMPS) system&#39;s operating parameters to optimize efficiency, remove hot spots and isolate faults by integrating a microcontroller, PWM digital circuits and analog circuits into a single integrated circuit, e.g., a mixed signal device, thereby reducing the number of external connections, silicon die area and integrated circuit packages. A lossless inductor current sense technique integrates a matched, tunable complimentary filter with the intelligent SMPS controller for accurately measuring current through the power inductor of the SMPS without introducing losses in the power circuit. The complimentary filter is adjusted by the microcontroller to significantly reduce the effects of component tolerances, accurately measuring the power inductor current for precise closed loop control and over current protection. The frequency pole and gain of the complimentary integrated filter can be adjusted on the fly in order to adapt to dynamically changing operating conditions of the SMPS system.

RELATED PATENT APPLICATIONS

This application claims priority to commonly owned U.S. ProvisionalPatent Application Ser. No. 61/418,183; filed Nov. 30, 2010; U.S. patentapplication Ser. No. 13/159,000; filed Jun. 13, 2011; and U.S. patentapplication Ser. No. 13/159,090; filed Jun. 13, 2011; all of which arehereby incorporated by reference herein for all purposes.

TECHNICAL FIELD

The present disclosure relates to switch mode power supplies, and, moreparticularly, to efficiency-optimizing, calibrated sensorlesspower/energy conversion in a switch-mode power supply (SMPS).

BACKGROUND

The synchronous buck switch-mode power converter is a commonly usedtopology for switch-mode power supply (SMPS) applications. The SMPStopology is gaining wider acceptance because of its high efficiency,small size and light weight. However, as the size of an SMPS isdecreased, heat dissipation/removal therefrom becomes more problematic.Even though the typical efficiency of an SMPS may be 90 percent, therestill remains 10 percent of the energy used by the SMPS becoming wastedheat. In addition, the high efficiency of the SMPS is optimized for onlya single load condition. However, in real world applications powerutilization loads vary over a wide range, and so do the associated SMPSefficiencies at those loads. Current sensing in the SMPS topology can bechallenging and must be overcome in design. Knowing or monitoring thecurrent being injected into the load provides protection for the powerconverter and can improve dynamic performance during closed loop controlthereof.

Inductors in the SMPS are used to store energy during a portion of theswitching cycle. The electrical characteristics, e.g., inductance andmagnetic saturation values, of the SMPS inductor may vary widely. Thetolerance of the inductor characteristics varies with temperature and/orvoltage, so SMPS systems must be “over-designed” to optimize SMPS systemefficiency for worst case conditions. Also, accurate measurement of theinductor current from one SMPS to another and at different load currentsbecomes problematic. Having the ability to accurately calibrate inductorcurrent sense circuits associated with the inductors of a multiphaseSMPS system would improve the dynamic performance and eliminate hotspots for the multiple phase converters of the multiphase SMPS system.

SUMMARY

Therefore a need exists for a higher performance power/energy conversionswitch-mode power supply (SMPS) that maintains improved efficiencies forsubstantially all load conditions. This may be accomplished with anintelligent pulse width modulation (PWM) controller that adapts the SMPSsystem operating parameters to optimize efficiency, remove hot spots andisolate faults by integrating a microcontroller, PWM digital circuitsand analog circuits into a single integrated circuit, thereby reducingthe number of external connections, silicon die area and integratedcircuit packages then have been required by prior technology SMPSsystems. Thereby allowing smaller printed circuit board space and fewerexternal components that result in lower cost to manufacture andimproved reliability of the SMPS system.

These improved efficiencies available for substantially all loadconditions may be achieved by combining intelligent control and the useof pulse width modulation (PWM) with calibrated sensorless feedbacktechniques more fully described hereinafter. According to the teachingsof this disclosure, the intelligent SMPS controller may be programmed tooptimize SMPS efficiencies for all operating parameters, e.g., switchingfrequencies, delay time between switches, drive capabilities, etc., oversubstantially all load conditions of the SMPS.

According to a specific example embodiment of this disclosure, aswitch-mode power supply (SMPS) comprises: at least one power switchcoupled to a voltage source; a power inductor coupled to the at leastone power switch; a filter capacitor coupled to a load side of the powerinductor that provides a regulated voltage output of the SMPS; and aSMPS controller coupled to the voltage source, the at least one powerswitch, the power inductor and the regulated voltage output of the SMPS,wherein the SMPS controller comprises: at least one driver coupled tothe at least one power switch; a pulse width modulation (PWM) generatorhaving an output coupled to and controlling the at least one driver; adigital processor having a memory, the digital processor is coupled toand provides operating parameters to the PWM generator during operationthereof; a voltage comparison circuit for comparing the regulated outputvoltage to a reference voltage, wherein the voltage comparison circuitgenerates an error signal representative of a difference between theregulated output voltage and the reference voltage, and wherein theerror signal is coupled to an error input of the PWM generator; and asensorless tunable complimentary filter coupled to the power inductor,wherein the sensorless tunable complimentary filter measures currentthrough the power inductor and provides a voltage output to the digitalprocessor that is representative of the current flowing through thepower inductor; wherein the digital processor optimizes operation of theSMPS by providing operating parameters to the SMPS controller for alloperating conditions of the SMPS.

According to another specific example embodiment of this disclosure, amethod for optimizing operation of a switch-mode power supply (SMPS),said method comprises the steps of: providing at least one power switchcoupled to a voltage source; providing a power inductor coupled to theat least one power switch; providing a filter capacitor coupled to aload side of the power inductor that provides a regulated voltage fromthe SMPS; and providing a SMPS controller, wherein the SMPS controllerfacilitates: coupling at least one driver to the at least one powerswitch, controlling the at least one driver with a pulse widthmodulation (PWM) generator, comparing the regulated voltage from theSMPS to a reference voltage with a voltage comparison circuit,generating a voltage error signal representative of a difference betweenthe regulated voltage and the reference voltage with the voltagecomparison circuit, coupling the voltage error signal to the PWMgenerator, measuring current through the power inductor with asensorless tunable complimentary filter coupled to the power inductor;providing a current output signal representative of the current flowingthrough the power inductor with the sensorless tunable complimentaryfilter, providing a digital processor having a memory, wherein thevoltage error signal and the current output signal are coupled to inputsof the digital processor and the digital processor controls the PWMgenerator for adjusting operating parameters based upon the currentoutput and voltage error signals.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present disclosure thereof may beacquired by referring to the following description taken in conjunctionwith the accompanying drawings wherein:

FIG. 1 illustrates a schematic block diagram of a basic voltageregulator system;

FIG. 2 illustrates a more detailed schematic block diagram of thevoltage regulator system shown in FIG. 1;

FIG. 3 illustrates a schematic diagram of the power circuit shown inFIG. 2 implemented as a switch-mode power supply (SMPS), according to aspecific example embodiment of this disclosure;

FIG. 4 illustrates a more detailed schematic block diagram of thecontrol circuit shown in FIG. 2, according to the specific exampleembodiment of this disclosure;

FIG. 5 illustrates a schematic diagram of a circuit for losslesslymeasuring inductor current of a SMPS, according to a specific exampleembodiment of this disclosure;

FIG. 6 illustrates a schematic diagram of a circuit for losslesslymeasuring inductor current of a SMPS, according to another specificexample embodiment of this disclosure;

FIG. 7 illustrates a graph of pole frequency adjustments for thecircuits shown in FIGS. 5 and 6;

FIG. 8 illustrates a graph of DC gain adjustments for the circuits shownin FIGS. 5 and 6; and

FIG. 9 illustrates a schematic block diagram of a mixed signalintegrated circuit device for controlling a SMPS system using thespecific example embodiments of the tunable complimentary filters shownin FIGS. 5 and 6.

While the present disclosure is susceptible to various modifications andalternative forms, specific example embodiments thereof have been shownin the drawings and are herein described in detail. It should beunderstood, however, that the description herein of specific exampleembodiments is not intended to limit the disclosure to the particularforms disclosed herein, but on the contrary, this disclosure is to coverall modifications and equivalents as defined by the appended claims.

DETAILED DESCRIPTION

Referring now to the drawing, the details of specific exampleembodiments are schematically illustrated. Like elements in the drawingswill be represented by like numbers, and similar elements will berepresented by like numbers with a different lower case letter suffix.

In a general sense, a power converter can be defined as a device whichconverts one form of energy into another on a continuous basis. Anystorage or loss of energy within such a power system while it isperforming its conversion function is usually identical to the processof energy translation. There are many types of devices which can providesuch a function with varying degrees of cost, reliability, complexity,and efficiency.

The mechanisms for power conversion can take many basic forms, such asthose which are mechanical, electrical, or chemical processing innature. The focus herein will be on power converters which performenergy translation electrically and in a dynamic fashion, employing arestricted set of components which include inductors, capacitors,transformers, switches and resistors. How these circuit components areconnected is determined by the desired power translation. Resistorsintroduce undesirable power loss. Since high efficiency is usually anoverriding requirement in most applications, resistive circuit elementsshould be avoided or minimized in a main power control path. Only onrare occasions and for very specific reasons are power consumingresistances introduced into the main power control path. In auxiliarycircuits, such as sequence, monitor, and control electronics of totalsystem, high value resistors are common place, since their losscontributions are usually insignificant.

Referring to FIG. 1, depicted is a schematic block diagram of a basicvoltage regulator system. A power system 102, e.g., a basic switch-modepower converter where an input of an uncontrolled source of voltage (orcurrent, or power) is applied to the input of the power system 102 withthe expectation that the voltage (or current, or power) at the outputwill be very well controlled. The basis of controlling the output is tocompare it to some form of reference, and any deviation between theoutput and the reference becomes an error. In a feedback-controlledsystem, negative feedback is used to reduce this error to an acceptablevalue, as close to zero as is required by the system. It is desirable,typically, to reduce the error quickly, but inherent with feedbackcontrol is the trade-off between system response and system stability.The more responsive the feedback network is, the greater becomes therisk of instability.

At this point, it should be mentioned that there is another method ofcontrol—feed forward. With feed forward control, a control signal isdeveloped directly in response to an input variation or perturbation.Feed forward is less accurate than feedback since output sensing is notinvolved, however, there is no delay waiting for an output error signalto be developed, and feed forward control cannot cause instability. Itshould be clear that feed forward control typically is not adequate asthe only control method for a voltage regulator, but it is often usedtogether with feedback to improve a regulator's response to dynamicinput variations.

Referring to FIG. 2, depicted is a more detailed schematic block diagramof the voltage regulator system shown in FIG. 1. The power system 102has been separated into two blocks: the power circuit 206 and thecontrol circuit 208. The power circuit 206 handles the power system loadcurrent and is typically large, robust, and subject to wide temperaturefluctuations. Its switching functions are by definition, large-signalphenomenon, normally simulated in most stability analyses as just atwo-state switch with a duty cycle. The output filter (not shown) isalso considered as a part of the power circuit 206, but can beconsidered as a linear block. The control circuit 208 will normally bemade up of a gain block, an error amplifier, and a pulse-widthmodulator, used to define the duty cycle for the power switches.According to the teachings of this disclosure, the control circuit 208is optimized to respond to disturbances in the power system 102 whilemaintaining a desired output voltage, V_(OUT).

Referring to FIG. 3, depicted is a schematic diagram of the powercircuit shown in FIG. 2 implemented as a switch-mode power supply(SMPS), according to a specific example embodiment of this disclosure.The power circuit 206 of the SMPS may comprise a power source 320, e.g.,battery, a power inductor 312, high and low switches 316 and 318,respectively, e.g., power field effect transistors; a load capacitor 310for smoothing alternating current (AC) ripple from the desired directcurrent (DC) output, and a boot voltage capacitor 314. The power circuit206 is connected to and controlled by the control circuit 208 as shownin FIG. 4 and more fully described hereinafter.

Referring to FIG. 4, depicted is a more detailed schematic block diagramof the control circuit shown in FIG. 2, according to the specificexample embodiment of this disclosure. The control circuit 208 isconnected to the power circuit 206 shown in FIG. 3 and comprises adigital processor with memory 462, e.g., microcontroller; high and lowswitch drivers having deadband logic represented by function block 464,bias generator, current and voltage reference circuits 466; under andover voltage detectors 456, a PWM generator 458, an over currentdetector 454, a voltage comparison circuit 452, and a sensorlessinductor current measurement circuit 450. The PWM generator 458 may beof either an analog or digital design for supplying PWM control pulsesto the high and low switch drivers 464.

The high and low switch drivers of the function block 464 are coupled toand control when the high and low switches 316 and 318 turn on and off.In addition the deadband logic of the function block 464 prevent thehigh and low switches 316 and 318 from ever being on at the same time,preferably, there is a deadband where both of the high and low switches316 and 318 are off. The PWM generator 458 controls when and for howlong the power inductor 312 is coupled to and being charged by the powersource 320.

The boot voltage capacitor 314 supplies power to the high side portionof the switch driver 464; and the bias generator, current and voltagereference circuits 466. The bias generator, current and voltagereference circuits 466 supply precision current and voltage referencevalues to the current and voltage circuits 452, 454 and 456. The voltagecomparison circuit 452 measures the output voltage and compares it to areference voltage, V_(REF), from the voltage reference circuit 466. Anerror signal from the voltage comparison circuit 452, representing thedifference between a desired voltage value and the actual output voltagevalue, is applied to an error input of the PWM generator 458, whereinthe PWM generator 458 adjusts its pulse waveform output to minimize thatdifference (closed loop feedback, see FIG. 1). The over current detector454 monitors the current to the power inductor 312, and the under andover voltage detectors 456 monitor the input voltage to the SMPS forundesirable e.g., abnormal, conditions, e.g., inductor current exceedsallowable design limits, input voltage is above or below a designoperating input voltage range. The sensorless inductor currentmeasurement circuit 450 losslessly measures SMPS power inductor current,as shown in FIGS. 5 and 6 and more fully described hereinafter.

The sensorless inductor current measurement circuit 450 may beimplemented as a matched complimentary filter by utilizing a tunablefilter comprising an operational transconductance amplifier (OTA), avariable resistor and a variable capacitor in one specific exampleembodiment (FIG. 5). In another specific example embodiment, anoperational amplifier, configured as a buffer, and a variable resistorhave been added, providing independent gain and pole location adjustment(FIG. 6).

Referring to FIG. 5, depicted is a schematic diagram of a circuit forlosslessly measuring the power inductor current of the SMPS, accordingto a specific example embodiment of this disclosure. A tunablecomplimentary filter inductor current measuring circuit comprises anoperational transconductance amplifier (OTA) 522, a variable resistor524, and a variable capacitor 526. The OTA 522 is configured as avoltage variable integrator and is used as a first-order low-pass filter(see FIGS. 7 and 8). The transfer function for this integrator is:V ₀/(V ₁₁-V ₁₂)=g _(m)/(s*C _(F))

The OTA 522 circuit shown in FIG. 5 has an adjustable pole frequency,and adjustable DC gain. The pole frequency is adjusted by the capacitor526, C_(F), and resistor 524, R_(F); and the DC gain is adjusted by theresistor 524, R_(F). The transfer function of the filter shown in FIG. 5is represented by:V ₀/(V ₁₁-V ₁₂)=(g _(m) R _(F))/(s*R _(F) *C _(F)+1)As noted from the transfer function, the DC gain is equal to gm*R_(F);and the pole frequency is equal to 1/(2π*R_(F)*C_(F)) Hz. The polefrequency and DC gain can not be adjusted independently.

Referring to FIG. 6, depicted is a schematic diagram of a circuit forlosslessly measuring the power inductor current of the SMPS, accordingto another specific example embodiment of this disclosure. A tunablecomplimentary filter inductor current measuring circuit comprises anoperational transconductance amplifier (OTA) 522, a variable resistor624, an operational amplifier 628 configured as a buffer, a variableresistor 630, and a variable capacitor 526. The OTA 522 is configured asa voltage variable input gain stage with a wide bandwidth. Theoperational amplifier 628 decouples the input gain stage from the singlepole, low pass filter. The pole frequency can be adjusted by changingthe resistor 624, R_(F), and/or the capacitor 526, C_(F), and the DCgain can be subsequently adjusted by changing the variable resistor 630,R_(G). The transfer function of the filter shown in FIG. 6 isrepresented by:V ₀/(V ₁₁-V ₁₂)=(g _(m) *R _(G))/(s*R _(F) *C _(F)+1)As noted from the transfer function, the DC gain is equal tog_(m)*R_(G); and the pole frequency is equal to 1/(2π*R_(F)*C_(F)) Hz.The pole frequency and DC gain can be adjusted independently.

The tunable complimentary filters shown in FIGS. 5 and 6 can beadjusted, e.g., tuned, to match the L/R_(L) zero, and gain adjusted toamplify the sensed current signal to a desired voltage level. Thetunable complimentary filters can further be adjusted in-circuit tosignificantly reduce the effects of component tolerances. The tunablecomplimentary filters can be adjusted on the fly in order to adapt tochanging operating conditions of the SMPS. The tunable complimentaryfilters may be used to accurately measure the current through the powerinductor 312 for precise closed loop control of the SMPS over alloperating conditions so that the SMPS efficiency can be maximized by thedigital processor 462 through the PWM generator 458. The sensorlessinductor current measurement circuit 450 described hereinabove may alsobe used to monitor over current through the power inductor, thus takingthe place of an eliminating the separate over current detector 454.

The lossless current measurement circuits shown in FIGS. 5 and 6,accurately measure current through the SMPS power inductor 312 withoutwasting power, are highly accurate over all operating conditions, andare flexible and low in cost to implement in a mixed signal integratedcircuit 208 (FIG. 4).

Referring to FIG. 7, depicted is a graph of pole frequency adjustmentsfor the circuits shown in FIGS. 5 and 6.

Referring to FIG. 8, depicted is a graph of DC gain adjustments for thecircuits shown in FIGS. 5 and 6.

Referring to FIG. 9, depicted is a schematic block diagram of a mixedsignal integrated circuit device for controlling a SMPS system using thespecific example embodiments of the tunable complimentary filters shownin FIGS. 5 and 6. The mixed signal integrated circuit device 902 (e.g.,in an integrated circuit package having external electrical connections)comprises a SMPS controller 904, power transistor drivers 906 (e.g.,function block 464 of FIG. 4), a microcontroller 908 (e.g., digitalprocessor) and associated memory 910 (may be part of the microcontroller908), an OTA 622, an operational amplifier 728, a DC gain settingresistor 730, a pole frequency setting resistor 624, and a polefrequency setting capacitor 626. The SMPS controller 904 may generate apulse width modulation (PWM), pulse frequency modulation (PFM), pulsedensity modulation (PDM), etc., signal for controlling the powertransistor drivers 906 that provide the power control signals to thepower MOSFET switches 316 and 318 of the SMPS. The SMPS controller 904monitors the voltage regulated output voltage, V_(OUT), and the measuredinductor current signal, V₀, from the tunable complimentary filtercomprising OTA 622, operational amplifier 728, variable resistors 624and 730, and tuning capacitor 626.

The OTA 622, operational amplifier 728, variable resistors 624 and 730,and tuning capacitor 626 are connected and operate as more fullydescribed hereinabove. The microcontroller 908 may control the variableresistors 624 and 730, as well as setting parameters for the SMPScontroller 904 (dotted lines represent control signals). It iscontemplated and within the scope of this disclosure that themicrocontroller 908 can perform the same functions as and replace theSMPS controller 904. The microcontroller 908 has analog inputs andanalog-to-digital conversion circuits (not shown). An operating programfor the mixed signal integrated circuit device 902 may be stored in thememory 910 associated with the microcontroller 908. An additionalcapacitor 626 a may be added external to the mixed signal integratedcircuit device 902 and in parallel with the internal capacitor 626. Themicrocontroller 908 may control the capacitance value of the capacitor626, and in combination with control of the variable resistors 624 and730. Control of the capacitor 626 and/or variable resistors 624 and 730by the microcontroller 908 allows dynamic tuning of the gain and/or polefrequency of the tunable complementary filter complimentary filter onthe fly for optimal current measurement under changing operatingconditions of the SMPS. The tunable complimentary filterimplementation(s), according to the teachings of this disclosure canalso be applied, but is not limited to, switch-mode power converters(e.g., SMPS), brushless dc motors, etc.

While embodiments of this disclosure have been depicted, described, andare defined by reference to example embodiments of the disclosure, suchreferences do not imply a limitation on the disclosure, and no suchlimitation is to be inferred. The subject matter disclosed is capable ofconsiderable modification, alteration, and equivalents in form andfunction, as will occur to those ordinarily skilled in the pertinent artand having the benefit of this disclosure. The depicted and describedembodiments of this disclosure are examples only, and are not exhaustiveof the scope of the disclosure.

What is claimed is:
 1. A switch-mode power supply (SMPS), said SMPScomprising: at least one power switch coupled to a voltage source; apower inductor coupled to the at least one power switch; a filtercapacitor coupled to a load side of the power inductor that provides aregulated voltage output of the SMPS; and a SMPS controller coupled tothe voltage source, the at least one power switch, the power inductorand the regulated voltage output of the SMPS, wherein the SMPScontroller comprises: at least one driver coupled to the at least onepower switch; a pulse width modulation (PWM) generator having an outputcoupled to and controlling the at least one driver; a digital processorhaving a memory, the digital processor is coupled to and providesoperating parameters to the PWM generator during operation thereof; avoltage comparison circuit for comparing the regulated output voltage toa reference voltage, wherein the voltage comparison circuit generates anerror signal representative of a difference between the regulated outputvoltage and the reference voltage, and wherein the error signal iscoupled to an error input of the PWM generator; and a sensorless tunablecomplimentary filter coupled to the power inductor, wherein thesensorless tunable complimentary filter measures current through thepower inductor and provides a voltage output to the digital processorthat is representative of the current flowing through the powerinductor; wherein the digital processor optimizes operation of the SMPSby providing operating parameters to the SMPS controller for alloperating conditions of the SMPS.
 2. The SMPS according to claim 1,wherein the sensorless tunable complimentary filter, comprises: anoperational transconductance amplifier (OTA) having a first inputcoupled to the power inductor at the at least one power switch sidethereof, a second input coupled to a load side of the power inductor anda current output; an adjustable resistor coupled between the currentoutput of the OTA and a return of the voltage source; and a tuningcapacitor coupled between the current output of the OTA and the returnof the voltage source; wherein the voltage output from the tunablecomplimentary filter is available at a common node of the current outputof the OTA and the adjustable resistor.
 3. The SMPS according to claim2, wherein a pole frequency of the tunable complimentary filter isadjusted to match a zero frequency of the power inductor by changing aresistance of the adjustable resistor.
 4. The SMPS according to claim 2,wherein a pole frequency of the tunable complimentary filter is adjustedto match a zero frequency of the power inductor by changing acapacitance of the tuning capacitor.
 5. The SMPS according to claim 1,wherein the sensorless tunable complimentary filter, comprises: anoperational transconductance amplifier (OTA) having a first inputcoupled to the power inductor at the at least one power switch sidethereof, a second input coupled to a load side of the power inductor anda current output; an operational amplifier configured as a bufferamplifier and having an input coupled to the current output of the OTA;a first adjustable resistor coupled between the current output of theOTA and a return of the voltage source; a second adjustable resistorhaving a first end coupled to an output of the operational amplifier;and a tuning capacitor coupled between a second end of the secondadjustable resistor and the return of the voltage source; wherein thevoltage output from the sensorless tunable complimentary filter isavailable at the second end of the second adjustable resistor.
 6. TheSMPS according to claim 5, wherein a pole frequency of the tunablecomplimentary filter is adjusted to match a zero frequency of the powerinductor by changing a resistance of the second adjustable resistor. 7.The SMPS according to claim 5, wherein a pole frequency of the tunablecomplimentary filter is adjusted to match a zero frequency of the powerinductor by changing a capacitance of the tuning capacitor.
 8. The SMPSaccording to claim 1, wherein the SMPS controller is a mixed signalintegrated circuit fabricated on an integrated circuit die.
 9. The SMPSaccording to claim 1, wherein the SMPS controller further comprises: anover current detection circuit having an overcurrent detected outputcoupled to the digital processor; an under and over voltage detectioncircuit having an under or over voltage detected output coupled to thedigital processor; and a bias generator, and current and voltagereferences.
 10. The SMPS according to claim 9, wherein the SMPScontroller is a mixed signal integrated circuit fabricated on anintegrated circuit die.
 11. The SMPS according to claim 9, wherein theSMPS controller integrated circuit die is packaged in an integratedcircuit package having external electrical connections.
 12. The SMPSaccording to claim 1, further comprising an external tuning capacitorcoupled to the tuning capacitor.
 13. A method for optimizing operationof a switch-mode power supply (SMPS), said method comprising the stepsof: providing at least one power switch coupled to a voltage source;providing a power inductor coupled to the at least one power switch;providing a filter capacitor coupled to a load side of the powerinductor that provides a regulated voltage from the SMPS; and providinga SMPS controller, wherein the SMPS controller facilitates comprises thesteps of: coupling at least one driver to the at least one power switch,controlling the at least one driver with a pulse width modulation (PWM)generator, comparing the regulated voltage from the SMPS to a referencevoltage with a voltage comparison circuit, generating a voltage errorsignal representative of a difference between the regulated voltage andthe reference voltage with the voltage comparison circuit, coupling thevoltage error signal to the PWM generator, measuring current through thepower inductor with a sensorless tunable complimentary filter coupled tothe power inductor; providing a current output signal representative ofthe current flowing through the power inductor with the sensorlesstunable complimentary filter, providing a digital processor having amemory, wherein the voltage error signal and the current output signalare coupled to inputs of the digital processor and the digital processorcontrols the PWM generator for adjusting operating parameters based uponthe current output and voltage error signals.
 14. The method accordingto claim 13, wherein the steps of adjusting the operating parametersfurther comprises the step of optimizing operation of the SMPS for alloperating conditions thereof.
 15. The method according to claim 13,further comprising the step of adjusting a pole frequency of the tunablecomplimentary filter while measuring current through the power inductor.16. A method for optimizing operation of a switch-mode power supply(SMPS), said method comprising the steps of: providing a first powerswitch coupled to a voltage source; providing a second power switchcoupled between the first power switch and a voltage source return;providing a power inductor coupled to the first and second powerswitches; providing a filter capacitor coupled to a load side of thepower inductor that provides a regulated voltage from the SMPS; andproviding a SMPS controller, wherein the SMPS controller comprises thesteps of: driving the first power switch with a first driver, drivingthe second power switch with a second driver, controlling the first andsecond drivers with first and second pulse width modulation (PWM)signals, respectively, from a PWM generator, comparing the regulatedvoltage from the SMPS to a reference voltage with a voltage comparisoncircuit, generating a voltage error signal representative of adifference between the regulated voltage and the reference voltage withthe voltage comparison circuit, coupling the voltage error signal to thePWM generator, measuring current through the power inductor with asensorless tunable complimentary filter coupled to the power inductor;providing a current output signal representative of the current flowingthrough the power inductor with the sensorless tunable complimentaryfilter, providing a digital processor having a memory, wherein thevoltage error signal and the current output signal are coupled to inputsof the digital processor and the digital processor controls the PWMgenerator for adjusting operating parameters based upon the currentoutput and voltage error signals.
 17. The method according to claim 16,wherein the operating parameters of the PWM generator are selected fromany one or more of the group consisting of percent on times of thepulses of the first and second PWM signals, drive currents to the firstand second power switches, off times between on times of the first andsecond power switches, and PWM pulse rate per second (frequency).